Lapping apparatus



March 26, 1940- D. A. WALLACE LAPPING APPARATUS Filed 001;. '7, 1937 3Sheets-Sheet, 1

W lla/lid NAM. 5/. M w m A. m V L w A TTORNEYS.

March 26, 1940.

D. A. WALLACE LAPPING APPARATUS Filed Oct. 7, 19:57

3 Sh ets-Sheet 2 ATTORNEYS.

March 26, 1940. WALLACE 2,195,057

' LAPPING APPARATUS Filed Oct. 7, 1937 3 shee ts sheet 3 INVENTOR DA V/D A. WALL/ 0E gg m fMfaZafi W A TTORNE Y5 Patented Mar. 26, 1940 LAPPINGAPPARATUS David A. Wallace, Detroit, Mich, assignmto ChryslerCorporation, Highland Park, Mich.) a corporation of Delaware ApplicationOctober 7, 1937, Serial No. 167,804 I 3 Claims.

This invention relates to an improved lapping apparatus.

More particularly, the invention pertains to an improved apparatus forlapping end surfaces 5 such as the crowned ends of tappets and similararticles of the type commonly used in internal combustion engines andcompressors.

One of the main objects of the invention is the provision of lappingapparatus of this charlO acter by which such relative movements betweena lapping element and the surface operated upon are produced that tl epossibility of retracing of scratch lines in the surface is guardedagainst.

Another object of the invention is the provision of apparatus of thiskind which is adapted to bring a lapping element into conformity withsuccessively adjacent portions of crowned surfaces of differentcurvatures.

A further object of the invention is the provision of an improveddriving connection between a lapping element of a tool and its drivingmember which accommodate self-adjustment of the operative surface of thelapping element to crown surfaces of different pieces of work.

Still further objects of the invention are to provide a lapping machineby which a plurality of pieces of work can be simultaneously lapped fora predetermined period of time; to provide a machine of this type whichautomatically predetermines the lapping period and which, at the end ofthe lapping period on one piece of work, discontinues the drive of thatpiece and moves the lapping tool which has been operating thereon, intoan unobstructing position to facilitate convenient loading and unloadingof the work while a plurality of other pieces of work are being lapped.

An illustrative embodiment of the invention is shown in the accompanyingdrawings, in which:

Fig. 1 is a top plan view, partly in section, and showing portionsremoved to disclose the underlying structure, of a machine embodying theinvention.

Fig. 2 is a transverse vertical sectionalview taken on the line 2-2 ofFig. 1.

Fig. 3 is a fragmentary vertical sectional view taken on the line 3-3 ofFig. 2.

Fig. 4 is a fragmentary radial sectional view taken on the line 4-4 ofFig. 1.

Fig. 5 is a fragmentary vertical sectional view taken on the line 5-5 ofFig. 2.

Fig. 6 is a fragmentary horizontal sectional view taken onthe line 66 ofFig. 5.

Fig. 7 is an end elevational view of the structure shown in Fig. 5 andtaken as illustrated by the line '|--'l of the latter figure.

Fig. 8 is a fragmentary vertical sectional view taken on the line 8-8 ofFig. 2.

In the form of the invention shown in the drawings, the lappingapparatus includes a stationary base structure, generally designated bythe numeral "I, having a central, vertically up- -standing hub part IIin which a hollow spindle I2 is rotatably supported by rolling contactmembers l3 and M. Non-rotatabl'y fixed to the spindle I2 is a worksupporting carriage E5 of circula1 shape having a central opening itthrough which the spindle I2 extends. The top portion of the worksupporting carriage I5 is detachably secured to a radial flange llextending outwardly from the spindle I! by cap screws l8. Provided onthe work supporting carriage i5 are a plurality of arcuately spacedwork-holding members, generally designated by the numeral HQ in Figs. 2and 4. Each work-holding member includes a sleeve 20 seated in anopening 2| in the carriage I5 and detachably secured to the latter bycap screws 22. Provided in the interior of each sleeve 2!! is a pair ofrolling contact bearings 23 in which a tubular spindle 24 is rotatablysupported. The tubular spindle 24 has an open upper end portion forreceiving the stem part 25 of a tappet 26. A plug member 21 extendinginto the lower end portion of the tubular spindle 24. has an upperextremity so formed as to provide a seat for the lower end portion ofthe tappet stem 25. A pulley wheel 28 is mounted on the exterior of thetubular spindle 24 and non-rotatably secured to the latter by a key 29.Belts 30 extend around the circumferentially arranged and arcuatelyspaced series of work-holding members 59 and are engaged in the beltgrooves of the pulleys 28 thereof. The belts 30 also extend around adriving pulley 3! which is radially spaced outwardly from the series ofworkholding members in order to bring the belts out of contact with atleast the pulleys of one of the work-holding devices 19, asillustratedin Fig. 1. During rotation of the work supporting carriage I5, ashereinafter more clearly set forth, each successive work-holding deviceis moved into radial alignment with the driving pulley 3! in order tobring the pulley of each successive work-holding member out of operativeengagement with the belts 30.

The work supporting carriage i5 has a down! wardly extending lowerstructure on which is provided a worm gear ring 32 that is meshed with aworm 33 'by which the work supporting carriage i5 is drivingly rotatedabout the axis of the spindle I2. The drive pulley 3| of the workholding devices I9 and the worm 33 by which the work and tool carriagesare rotated are driven from a common source including, a pulley I00mounted on a shaft |0| which is journalled in housing I02. The pulleyI00 may be driven by a motor (not shown) or other suitable means and itsshaft |0| is provided with pinions I03 and I04 which transmit the driveto gears I05 and I06, respectively. The gear I05 is operativelyconnected with the worm 33 by belt and pulley apparatus, generallydesignated at I01, and the gear I06 is operatively connected by belt andpulley mechanism I08 and a shaft I09 with a gear unit 0, shown in Fig.3, by which the drive pulley 3| is operated. The gear unit IIO includesa housing I I I in which one end of the shaft I09 is journalled.- Ashaft I I2 having an axis disposed substantially normal to the shaft I09is journalled in the housing I I I and drivingly connected therewith bybevel gears ||3. The drive pulley 3| is non-rotatably fixed to anexternal end portion of the shaft 2. p

The rotatable work supporting carriage I5 is provided with a lubricantdischarge system which comprises discharge pipes 34 having their outletend portions located in close proximity to the end portions of thetappets 26 which are to be lapped. The pipes 34 communicate withpassages 35 in the Wall structure of the spindle I2 which leads from alubricant well 36 formed in the stationary base structure of themachine. The lubricant well 36 is supplied with lubricant through asystem of pipes, generally designated by the numeral 31. An upwardlyextending circular flange 38 is provided on the rotatable worksupporting carriage I5 for preventing outward throwing of lubricant. Thelubricant discharged from the pipes 34 upon the work is allowed to rundown into an annular trough 39 formed in the carriage I5 from which itis discharged into a well 40 provided in the stationary base structureID. The well 40 has an outlet pipe 4| communicating therewith forreturning lubricants to the base structure from which it was suppliedthrough the system of pipes 31.

Provided on the'upper end portion of the spindle I2 is a reduced endsection 42 on which is non-rotatably mounted a lapping tool carriage,generally designated by the numeral 43, and comprising a central sleeve44 on which radially extending arms 45 are detachably secured by capscrews 46. Each radially'extending arm 45 has a vertically extendingchannel-way 41 formed in its outer extremityfin which a lapping tool,generally designated by the numeral 48, is slidably mounted. Eachlapping tool 48 comprises a base structure 49 having flanges 50 slidablyengaged in the channel-ways 41 of the arms 45 and an electric motor 5|,or other suitable driving mechanism, having a shaft 52 on the lower endof which is mounted a disc 53. The driven shafts. 52 of each lappingtool are disposed above and associated with one of the work-holdingmembers I9, respectively. The rotative axis vof the driving shaft 52 maybe concentric with the axis of rotation of the work supported by thehollow spindles 24, but, for reasons hereinafter set forth, in thelapping of certain types of crowned surfaces, it is preferable to havethe axis of rotation of the shaft 52 arranged in eccentric relationshipwith respect to the axis of rotation. of the work.

A disc 54 having an inverted cup-shaped lapping element 55 preferablycomprising lapping thedisc 53 and which are threaded in counterboredapertures 58 in the disc 54. A coil spring 59 seated in the counterboreof the aperture 58 bears between the discs 53 and 54 so as to yieldablyurge the latter disc axially of the shaft 52 and to yieldably resistlateral movement of the disc 54 with respect to the disc 53. A drive pin60 mounted on the disc 53 is received in an oversize aperture 6|provided in the disc 54 for transmitting the drive from the shaft 52 tothe disc- 54 and lapping elements 55 carried thereby. The lappingelement 55 is preferably detachably mounted on the disc 54 by a screw 62and located on the disc 54 in eccentric relationship with respect to theaxis of rotation of the shaft 52.

In the form of the invention illustrated, electrical power is suppliedto the motors 5| of the lapping tool 48 by conductors 63 which extendthrough a tube 64 mounted on the base structure I0 of the machine andextending through a passage 65 in the spindle I2. Each of the conductors63 is electrically connected to a slip ring 66 mounted on the exteriorof the tube 64 and confined in ahousing 61 carried by and adapted torotate with the spindle I2. The slip rings 66 remain stationary duringrotation of the housing 61. Disposed in the housing 61 is a horizontalplate 68 on which posts 69 are mounted. Each post 69 is provided with abrush 10 which bears against one of the slip rings 66. The brushes 10rotate in unison with the casing 61 and spindle I2 and they establishelectrical connection between the slip rings 66 and bus bar rings 1|disposed in the housing 61, as illus trated in Fig. 2. Each electricalmotor 5| of the respective lapping tools 48 is provided with conductors12 which are respectively electrically connected with the bus bars-1|.

The lapping tools 48 normally assume their lowermost positions, asillustrated at the left in Fig. 2,by virtue of their weight. As eachlapping tool and its associated tool holding member I9, reaches theposition indicated by the numeral 13 in Fig. 1, at which the drivingconnection between the belt 30 and the work-holding member isinterrupted, the lapping tool is lifted to facilitate convenient removalof the tappet 26 after the latter has been lapped, and replacement of atappet to be lapped. in the work holder. This, is accomplished byproviding a lever 14 which is pivotally mounted on each of the arms 45of the tool carriage and arranged so that its outermost end engages thelower extremity of the base portion 49 of each lapping tool 5|,respectively. During rotation of the work and tool carriages I5 and 45,respectively, each of the tools 48 are successively lifted toaccommodate removal of the work 26 and replacement of work in thework-holding members 9. This is accomplished by the provision of camfollowers, generally designated by the numeral 15, which comprise rods16 slidably mounted in tubes 11 mounted in circumferentially arrangedapertures 18 in the central portion of the work supporting carriage I5.One cam following device 15 is provided for operating the lever 14 ofeachrespective lapping tool 48. The upper end portion mounted on theupper extremity of the hub portion H of the base structure ill. The camtrack BI is provided with an upwardly extending projection 82 whichlifts the cam follower associated with each respective lapping tool torotate the lever 14 thereof and lift the tool as the latter is movedinto the loading and unloading position designated by the numeral I3 inFig. 1.

During operation of the foregoing apparatus, a plurality of tappets orother articles are simultaneously lapped for a predetermined period oftime, as determined by the time required to produce one completerotation of the work carriage l5 from the loading and unloading station13. During this lapping period, the lapping element 55 is revolved Whilethe work is rotated; In the illustration shown in Fig. 4, the lappingelement 55 has an outer diameter slightly lessthan the diameter of thecrowned surface of the tappet being operated upon. Relative movementsaccommodated between the discs 54 which supports the lapping element 55and the discs 53 of the driven shafts 52 permits the working surface ofthe lapping element 55 to become accommodated to the curvature ofsuccessively adjacent portions of the crown surface of the tappet. Inthis manner all portions of the crown surface of the tappet aresubjected to uniform action of the lapping element 55, which by reasonof its revolving movement accompanied by the rotational movement of thework does not tend to retrace any of the scratch lines produced by thework by localized harsh particles of lapping material.

Although but one specific embodiment of the invention is herein shownand described, it' will be apparent that various changes in the size,shape and arrangement of parts may be made without departing from thespirit of my invention.

What I claim is:

1. Lapping apparatus comprising a work support, a spindle on said worksupport for drivingly rotating a piece of Work and retaining a surfaceof the latter which is disposed transversely of its axis of rotation inposition to receive a lapping operation, a lapping tool adjacent saidsup- .port including a rotative driving member having an extremity inopposed spaced relationshipwith respect to said surface, means forsupporting said driving member for rotation about an axis substantiallyparallel to but laterally spaced from the axis of said spindle, alapping device between said surface and said extremity of said drivingmember having a lapping surface engageable with said surface of saidwork and extending on respectively opposite sides of the axis ofrotation of the latter throughout the entire course of relative movementof said work and lapping surface, means drivingly connecting said memberand lapping device including connecting elements having loose fittingengagement with one thereof for accommodating movement of said lappingdevice axially and transversely of said driving member and soconstructed and ar ranged as to retain said lapping device ineccentricrelationship with repect to the rotative axis of said driving member andresilient members bearing between said driving member and said lappingdevice for yieldably urging the latter against said surface of saidwork.

2; Apparatus for lapping a crowned extremity of a tappet comprising asupport, a spindle on said support for drivingly rotating said tappetand retaining said crowned extremity thereof in position to receive alapping operation, a rotatable driving member adjacent said spindlehaving an axis parallel to the axis of the latter but spaced laterallytherefrom and having an end portion disposed in spaced opposedrelationship with respect to said tappet extremity, a lapping elementaxially slidably and transversely movably mounted on said extremity ofsaid driving member in eccentric relation with respect to its axis andhaving a ring shaped abrading surface provided with a central openingextending on respectively opposite sides of the rotative axis of saidwork throughout all portions of the course of relative movement of thelatter and said abrading surface engageable with the crowned surface ofsaid tappet, and resilient means for yieldably urging said lappingelement toward said tappet and adapted to accommodate movement of saidlapping element to conform with the crowned extremity of said tappetduring operation of said apparatus.

3. Apparatus for simultaneously lapping the ends of a plurality oftappets including a basestructure, a rotatable carriage on said basestructure having a pluralityof arcuately spaced rotatable membersthereon ach adapted to support a tappet with its end sur ace exposed toreceive a lapping operation, a t ol carriage rotatably mounted on saidbase structu e in axially spaced substantially concentric rel ionshipwith respect to the axis of said work carriage, a plurality of lappingtools each comprising a rotative driving member having a lapping elementaxially and laterally yieldably mounted thereon in ec-,

centric relationship with respect to its rotative axis, each tool beingso mounted on said tool carriage as to accommodate movement of itsrespective lapping element toward and away from an end surface of one ofsaid tappets respectively, means for simultaneously drivingly rotatingeach of said carriages, apparatusfor simultane-

